Resistance exercise (RE) may lower the need for insulin in gestational diabetes mellitus (GDM), according to the results of a randomized controlled trial reported online September 23 in the American Journal of Obstetrics and Gynecology.

"Because skeletal muscles represent the main site of insulin resistance observed during pregnancy, both the American College of Sports Medicine and the American College of Obstetricians and Gynecologists recommend exercise as an effective and safe supporting therapy for the treatment of GDM because several lines of evidence have shown the effectiveness of aerobic exercise in reducing the frequency of women using insulin," write Marcelo C. de Barros, MSc, from the University of São Paulo School of Medicine in Brazil, and colleagues. "On the other hand, little is known about the therapeutic application of [RE] to women with GDM."

The study goal was to assess the effect of an RE program using an elastic band on insulin requirement and glycemic control in 64 patients with GDM. Participants were randomly assigned 1:1 to an exercise group or a control group.

There were 7 women who needed insulin in the exercise group compared with 18 in the control group (P = .005). Similarly, the exercise group fared better than the control group in terms of percentage of time spent within the proposed target glucose range (at least 80% of weekly measurements below the limits preestablished for the disease). For the exercise group, this was 0.63 ± 0.30 compared with 0.41 ± 0.31 in the control group (P = .006).

"The [RE] program was effective in reducing the number of patients with GDM who required insulin and in improving capillary glycemic control in this population," the study authors write. "The present study provided evidence that RE may contribute to the care of patients with GDM."

Limitations of this study include small sample size and inability to determine the possible combined effects of RE with aerobic exercise and/or metformin in women with GDM.

"Further well-designed and controlled studies investigating the effects of RE on metabolic control in GDM should compare RE with aerobic exercise and should determine whether the adoption of both types of exercise may confer additional benefits," the study authors conclude. "In addition, the combined action of RE and metformin should be analyzed as well as whether the molecular mechanisms underlying the disease are modified by RE and whether RE is able to prevent the occurrence of GDM as observed for aerobic exercise."

The Coordenação de Aperfeiçoamento de Pessoal de Nível Superior supported this study by granting a master's fellowship.